Meteorologische Zeitschrift (Dec 2018)
The regional perspective of the 1.5 °C target and its difference to other scenarios
Abstract
We analyzed climate projections from CMIP5 to assess the global and regional differences between the 1.5 °C and the 2.0 °C target as well as the differences to the climate protection and the business as usual scenario. Due to the lack of scenarios leading to a global warming of 1.5 °C by the end of the 21st century, we choose for our analysis those time periods from the available CMIP5 simulations which show a global mean temperature of 1.5 °C (WP1.5) and 2.0 °C (WP2) above the pre-industrial level as representatives for such conditions. In our novel approach, we used the average over the last 200 years of the pre-industrial control simulation of each model as pre-industrial reference value for that model. Our analysis showed that tropical regions and regions located on the southern hemisphere show less warming compared to the global average and the strongest warming appears in the high northern latitudes. In some of the regions in the high northern latitudes, the additional warming is more pronounced in fall and especially in winter. To attach value to our analysis, we carried out several statistical tests which agreed, that the temperature values for WP1.5 are statistically significantly different from the temperature values in WP2 on the global, regional as well as on the seasonal level. The difference in the precipitation amount is small in all regions. This is underpinned by the results of statistical tests, which indicate that the precipitation values for the two warming periods are not significantly different for most of the regions. Regions in the high northern latitudes and continental regions would benefit more than tropical regions and regions on the southern hemisphere if global warming is limited to 1.5 °C instead of 2.0 °C. In the business as usual scenario the continental regions and the regions in the high northern latitudes are confronted with warming values which are 3 °C to 5 °C above the values of the respective region when the 1.5 °C target would be met.
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